This invention relates to a waterproof structure for a wire harness equipped in a vehicle such as an automobile.
In general, a connector in the wire harness, which is arranged outside of an interior of the vehicle, is constructed to have a waterproof structure in order not to cause leakage and corrosion due to immersion in water. However, in such a waterproof connector of a leak-tight structure, there is generated a phenomenon that, because of a pumping action caused by the change in temperature, water is sucked up via clearances between the electric wires of the wire connecting part of a connector thereby to immerse the interior thereof. Alternatively, there is the other phenomenon that since the water is sucked up by capillary action in the gaps between the wires, the connector then becomes immersed by the water.
In order to prevent the water from intruding through the wire connecting part, Japanese Unexamined Patent Publication (Kokai) No. 1-206573 and Japanese Examined Utility Model Publication (Kokoku) No. 4-41733 disclose waterproof joint structures in which the wire connecting parts of the connectors are covered with butyl rubber.
In the conventional waterproof joint structure, in an assembled state, the wire connecting part and the wires (part) are enclosed by a butyl rubber (sticky sealant), which is arranged inside an insulator sheet of chlorine vinyl, and then pressed from outside, whereby the waterproof joint can be provided. In this structure, the butyl rubber fills gaps between the wires thereby to prevent the water from intruding from outside.
However, in such a wire harness where some wire connecting parts are provided on the wires to a connector, if the conventional waterproof joint is attached only to the nearest wire connecting part to the connector and no joints are attached to the other parts, the following problems are raised.
That is, in the conventional waterproof joint, although the exterior of the joint is only covered with the butyl rubber and thus gaps between the wires are closed, gaps among core lines accomodated in an outer shell of the wire cannot be sealed yet. Consequently, although the conventional joint can prevent the water from intruding from outside, it is impossible to stop the flow of water which enters through the other wire connecting parts and then/flows between the core lines.
Although it is necessary to provide all wire connecting parts with the waterproof joint in order to intercept the immersion of water, such an arrangement incures the increasing cost and time to build up the arrangement.